Optical diffusion film is widely applied to light source-required devices such as LCD devices, advertising light boxes, lighting devices and mobile communication apparatus keys to provide uniform illumination.
In recent years, LCD (liquid crystal display) device grows apace and is widely applied in the display device of the mobile communication apparatus, notebook computer, desk-top computer and large-sized liquid crystal television. In addition, the optical diffusion film has increscent use in lighting device, which increases the requirement of the optical diffusion film for using in the LCD device and lighting device. The present study on the optical diffusion film is mainly concentrated on improving brightness.
However, in addition to the requirement for high brightness, the optical diffusion film needs good anti-abrasion property during the using process so as to prevent from abrasion or scratch. Specifically speaking, an optical diffusion film needs to be cut into a device-required size in advance during the using process, while a majority of the optical diffusion films can be subject to friction of conveyor belt during the cutting process in die cutting plant; the optical diffusion film after cutting is subject to abrasion by hands of operator during the packaging process; furthermore, friction between optical diffusion films tends to occur during the transportation process. Such various kinds of frictions can lead to damage of film appearance, which results in that the qualified percent of the films at client decrease. Additionally, the optical diffusion film in the lighting device is located outside the lamp, such that the film tends to be abraded or scratched during the cleaning process, which affects its use.
With respect to the above problems, the prior art improves the anti-abrasion property of the optical diffusion film primarily by increasing the strength of the resin binder, i.e., using resin reinforcing agent, in composition in the diffusion coating of the films, E.g., a patent application with publication No. CN101487902A discloses a novel environment-friendly anti-scraping prism film, using resin reinforcing agent to improve the anti-abrasion property of the film; and a patent application with publication No. CN2004461A “Anti-abrasion film and LCD”, a patent with publication No. CN100498460C “Anti-abrasion optical film and use thereof”, and a patent with publication No. CN100426008C “Anti-abrasion optical film and use thereof”, all adopt heating-and-UV curing process and concave-convex structure, substantially enhancing the strength of the resin, to improve the anti-abrasion property of the thin film.
However, the diffusion coating of the optical diffusion film contains diffusion particles, a large majority of which is exposed out of the diffusion coating; accordingly, the binding strength between the resin and the particles cannot be guaranteed if the strength of the resin is independently improved, such that the diffusion particles in the diffusion coating tend to be detached or abraded during the service process of the film, which affects the use of the optical diffusion film.
In the prior art, diffusion particles of single diameter or of narrow disperse diameter are mostly used in diffusion coating of the optical diffusion film, and tend to be abraded or detached in large area when the film receives external force such as friction or abrasion, resulting in large-area abrasion of the optical diffusion film.
It is therefore desirable to further improve the anti-abrasion property of the optical diffusion film, and to reduce the large-area abrasion or shedding of the diffusion particles when the optical diffusion film receives external force.